Generally, a lens substrate for polarized eyeglasses is prepared by integrating the lens substrate for eyeglasses with a polarizing element having a polarizing membrane (film), wherein the polarizing membrane is prepared by stretching uniaxially a resin film such as polyvinyl alcohol and impregnating the resultant with iodine or the like.
A lens substrate for eyeglasses used for visual correction includes a convex lens surface formed on its front surface, and a concave shape, a flat shape, etc. formed on its back surface. When the lens substrate is adjusted as an eyeglass lens to an appropriate optical power for a consumer, the back surface is sometimes ground while the front surface is not ground but applied with a coating containing any functional component.
For producing a lens substrate for polarized eyeglasses by a cast molding (casting) method, a production method is well known in which the circumference of a polarizing film pressure-molded in a hemispherical shape in advance is retained in the inner periphery of a ring-shaped gasket with the same diameter as the lens substrate, a pair of molds for forming concave⋅convex shaped lens surfaces is fixed integrally to the gasket with each mold placed at a predetermined distance away from the front and back surfaces of the polarizing film, a monomer is injected into a gap (cavity) which determines the lens thickness between the pair of molds and retained for a required period of time at a required temperature to undergo a polymerization reaction, and thus the cured resin is integrated with a polarizing element (see JP 2001-311804A).
Furthermore, in order for the lens substrate for eyeglasses to retain a functional component, for example, a method is known of applying in the form of a layer a coating liquid prepared by dispersing an infrared absorber in a binder resin on a surface of the lens and drying the resultant to form an infrared absorbing layer (see JP 2005-43921).
However, the above conventional technique of an eyeglass lens has not been able to exert sufficiently a required function such as a desired infrared absorbing performance when, in the case of the coating of an infrared absorber on the lens surface, the thickness of the coating layer is formed as thin as possible in order not to reduce the optical characteristics of the lens substrate.
In addition, when a costly function-imparting agent such as an ultraviolet ray absorber or an infrared absorber is dispersed and retained on a lens substrate for visual correction addressing myopia, a grinding operation for achieving a required optical power removes the most part of the lens substrate. The most part of the additional function-imparting agent is thus wasted without performing its function, which results in a poor efficiency of addition of a functionality-imparting agent. Therefore, a problem arises that the manufacturing cost increases.
In order to address above-described problems, in their previous patent application, inventors of the present invention formed, by way of insert molding of polyurethane resin materials, a polarizing element by coating both surfaces of a polarizing film with a polyurethane resin containing an infrared absorber and formed a lens substrate for eyeglasses used in grinding for adjustment of the optical power with a polyurethane resin which does not contain an infrared absorber, and then configured an infrared-absorbing lens substrate for polarized eyeglasses by integrally depositing the polarizing element on one surface of the lens substrate for eyeglasses (see JP 5075080).
However, as described above, when a lens substrate for polarized eyeglasses is produced by insert-molding a polarizing element formed by coating a resin containing an infrared absorber on both surfaces of a polarizing film and a lens substrate for eyeglasses used in grinding for adjustment of the optical power, the resin forming the front and back surfaces of the polarizing element has been already cured and an uncured resin layer is further formed thereon. This causes a problem in some cases that, depending on the resin type, the laminate integration is not good sufficiently, and that, especially for diethyleneglycol-bis-allylcarbonate (CR-39), the integration by lamination is unlikely to be ensured.
In addition, on the border between the resin layer formed in advance on one surface of the polarizing element and the second resin layer additionally formed on the resin layer during insert molding, an optically distinguishable interface is formed due to difference in flow direction of the resins during the molding, a difference in heat history of molding heat applied once or more, and the like. When such an eyeglass lens is subjected to what is called “prescription lens processing” to form a ground surface crossing the interface, a light shadow (a ring-shaped light shadow around the entire circumference of the lens) along the interface on the ground surface is visually confirmed, which leads to a problem that the quality of the lens for eyeglasses such as even transparency is ruined.
One problem of the present invention is to solve the above problems, in other words, to provide a composite functional polarized lens which has a good adhesive property in the interface without the occurrence of an optical spot on the border between lens substrates laminated in the polarized lens, has good efficiency of addition of a function-imparting agent for such as thermochromic, photochromic, ultraviolet ray and infrared ray absorption, and ensures sufficiently these additional functions. Another problem is, when a polarizing film is insert-molded (cast-molded), to provide a composite functional polarized lens which shows good adhesive integration by lamination regardless of the resin type.